Headlight



W. G. WOOD.

HEADLIGHT.

APPLlCATlON FILED DEC-24. I919.

1,395,026. Patented Oct. 25, 1921.

I NVENTOR WILL/f7 6'. W00

UNITED, STATES PATENT OFFICE.

WILLIAM G. WOOD, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOR TO BERKEL YLIGHT CORPORATION, OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OFNEVADA.

HEADLIGHT.

Specification of Letters Patent.

Patented Oct. 25, 1921.

To all whom it may concern:

Be it known that I, WILLIAM W000, a citizen of the United States,residmg at San Francisco, in the county of San Francisco and State ofCalifornia, have lnvented new and useful Improvements inIleadl-lghts, ofwhich the following is a specification.

This invention relates to headlights or projectors of the type shown anddescribed in my application, Serial No. 248,303, filed August 5, 1918,and the present apphcat on is in the nature of a continuation in part ofmy application, Serial No. 249,968 filed August 15, 1918.

.In said application, Serial No. 248,303 a cone-shaped beam having amlmmum of aberration is produced by reflecting light from a source inthe form of parallel rays and providing means to receive and project theparallel rays in the form of a coneshaped beam. It is the object of thepresent invention to sharpen the outline of the projected beam and tointensify the field of light. This I accomplish by placing an objectiveglass or lens in the front of the lamp housing where the rays of thecone-shaped beam converge and then locate a diaphragm at the principalfocal point of the objective lens, said diaphragm having an aperture-init whose greatest dimension is less than the diameter of the cone-shapedbeam at that point. Thereby, I am enabled to obtain a beam which, whenprojected on a screen or other light reflecting surface, gives a fieldof light which will be an exact image of the aperture in the diaphragmand which will be uniform in intensity and sharp in outline.

Forms which my invention may assume are exemplified in the followingdescription and illustrated in the accompanying drawings in which:

Figure 1 shows a vertical central sectional View of a lamp embodying myinvention.

Fig. 2 shows a detached view of one form of the diaphragm.

Fig. 3 shows a similar View of a modified form of diaphragm.

In the drawings I show an arrangement of reflectors similar to thoseshown in application Serial No. 248,303, although it is to be understoodthat any instruments capable of producing a cone-shaped beam may beemployed. It is preferable, however, to employ means which will reducethe spherical aberration to a minimum. A is a source of light, B is aparabolic reflector, and C a section or portion of a paraboloid, saidparts be1ng contained within a housing D of su1table form. The parallelrays from B are reflected by C in the form of a coneshaped beam. In thefront of the housing, at the point where the rays of the coneshaped beamcross, I place an objective glass or lens E whose focal length may varyaccording to the particular effect desired. At the principal focal pointof the objective lens, I place a diaphragm F formed with I an aperture Gwhose greatest dimension is slightly less than'the diameter of theconeshaped beam at that point. The shape of this aperture G may vary,and in Fig. 2 I show a segmental opening and in Fig. 3 a star-shapedopening.

IVith the diaphragm F in proper focus, the beam projected on a screen orother light reflecting surface at a distance in front of the lamp willexactly image the shape of the aperture in said diaphragm and will be ofuniform intensity and sharp outline, inasmuch as the aperture beingsomewhat reduced in size from the cross sectional area of the beam atthat point will have the effect of cutting out stray and faint rays atthe margin of the beam. In an automobile headlight, I find it desirableto use anaperture shaped like that shown in Fig. 2 which is a segment ofa' circle with the bottom part blocked off so that the image, which isalways an inverted one, will be approximately flat on top when projectedout from the lamp. The lamp is so positioned on the automobile that theuppermost rays of the projected beam are approximately horizontal and ofa height conforming to existing regulations, to wit, less than 42inches.

For other purposes, it may be desirable to use diaphragms havingapertures of a different shape, for instance, square, oval, or in theform of a star. The field of light projected from the lamp will alwaysbe in the form of the aperture in the diaphragm F.

lat

The diaphragm F is shown as mounted upon the reflector B, and it may, ifdesired, be adjustable so as to keep it in proper focus. The ad ustmenthere shown consists of a plate 10 .slidably mounted on a support 11,which latter serves to connect the two reflectors B and 0 together andretain them manufacture could be eliminated in the reflectors 'B and C,then the ob'ective lens E could be omitted and the sha ow cast by theapertured diaphragm would be exactly like the image which is projectedby the objective lens. By using the objective lens, instruments of lessexactness ma be embeing suificient merely if the rays of saidcone-shaped beam cross somewhere along the principal optical axis. ofthe-lens.

Various changes in the construction and arrangement ofthe several partsmay be employed without departing from the spirit of my invention asdisclosed in the appended claims.

, a reduced light emitting aperture, a source Having thus described myinvention, what I claim and desire to secure by Letters Patent is: I

1 In a headlight, a lamp housing having of light in said housing, meanscooperating with the source of light'for forming a coneshaped beam, anobjective lens positioned in the light emitting aperture where the raysof. the beam cross, and a diaphragm positioned at the principal focalpoint of the objective lens, said diaphragm having an aperture whose.greatset dimension is less than the diameter of the cone-sha ed beam atthat point, whereby stray and aint rays at the margin of the cone-sha'ed beam will be cut out and the field of hght projected will be an imageof the aperture in said diaphragm, the shape of the aperture in saiddiaphragm being such as to' produce a beam whose greatest diinensionisless than the ployed to produce the cone-shape beam, it\diameter of thecone-shaped beam at that point, whereby the faint and stray ra s' atthemargm of the converging beam Wlll be out out and the projected beamwill continue out in sharp outline.

3. In a headlight, a housing, a source of l1ght 'there1n, means forprojecting a substant1al portlon of the rays therefrom in a convergm.beam, an objective lens in the front of t e housing where the conver grays cross, and a diaphragm'positionefli tween the projecting means andlens at the principal focal point of the latter, said diaphragm'havingan aperture of smaller size than the ,cross-sectional'areaof theprojected beam at that point, whereb' faint and stray rays at the marginof the am are cut out and a field of light is produced outside of thehousing which is an-image of the aperture in the diaphragm.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

WILLIAM G. wooD.

Witnesses:-

W. W. Hmmr, VALERIE Dr. REMER.

